CN107073949B - Print head senses room circulation - Google Patents

Abstract

Print head has fluid slot and sensing room, which has first port and second port, which is connected to fluid slot.Sensing room includes ink sensor.Re-circulation path extends from fluid slot and is fluidically coupled to second port.Fluid pump circulates fluid through the re-circulation path.

Description

Print head senses room circulation

Background technique

Sometimes through using be located at print head on sensor come detect can be used for print head fluid or ink level or Amount.When print head, which is being used, not to be covered but, moisture may be from the fluid adjacent with sensor or ink evaporation.Moisture from Fluid loss may damage the performance of sensor.

Detailed description of the invention

Fig. 1 is the schematic diagram of sample printing head.

Fig. 2 is the flow chart for the exemplary method across sensing room circulation of fluid.

Fig. 3 be include Fig. 1 print system sample printing system schematic diagram.

Fig. 4 is the schematic diagram of the example implementation of the print head of the print system of Fig. 3.

Fig. 5 is the section view of the example implementation of the liquid level sensor of the print head of Fig. 3.

Fig. 6 is the circuit diagram of the liquid level sensor of Fig. 5.

Fig. 7 is the flow chart of the exemplary method for sensed level.

Fig. 8 is the schematic diagram of sample printing head used in print system for Fig. 3.

Fig. 9 is the flow chart for being used to form the exemplary method of print head.

Figure 10 is top view of the sample printing head before circulation path formation.

Figure 11 is top view of the print head of Figure 10 after circulation path formation.

Figure 11 A is the enlarged view of a part of the print head of Figure 11.

Specific embodiment

Fig. 1 schematically illustrates sample printing head 20.As will be hereinafter described, print head 20 is detected using sensor The liquid level of print head.Print head 20 refreshes such as black fluid circulation to sensor adjacent with sensor and by sensor The contained fluid of sensing.As a result, the service life or performance of sensor are enhanced.Print head 20 includes fluid slot 24, drop Generator 26 and level sensing systems 28.

Fluid slot 24 includes slot, and by the slot, such as black fluid is applied and is transported to associated with print head 20 Droplet generator 26.In one implementation, fluid slot 24 is formed in the substrate of such as silicon substrate.In one implementation, fluid Slot 24 extends along a column droplet generator 26, and wherein such as black fluid is supplied to each drop formation of the column by fluid slot 24 Device.

Droplet generator 26 includes on-demand dropping liquid (drop-on-demand) equipment, which generates individual Fluid drips and this drop of liquid fluid is discharged in a controlled manner.In illustrated example, droplet generator 26 includes beating Print causes room 30 and in room 30 or the initiation element 32 adjacent with room 30.Room 30 is fluidically coupled to the fluid in slot 24, To receive fluid or ink from slot 24.For the purpose of this disclosure, term " coupling " should mean that two components are direct or indirect Ground is coupled to each other.This connection can be substantially static or movable in nature.This connection can use each other Be formed integrally as single monolithic entity two components or two components and any additional intermediate member and realize, or using each other Two components or two components and any additional intermediate member of attachment and realize.This connection substantially can be permanent , or alternatively can be in itself removable or releasable.Term " fluidly couple " should mean two or More fluids transmission volume is connected to each other directly or is connected with each other by middle volume or space, allows fluid from one A volume flows into another volume.

Room 30 extends adjacent to nozzle opening 33, and wherein initiation element 32 includes that can operate to be sprayed by nozzle opening 33 The equipment of fluid drop out.In one example, droplet generator 26 includes the on-demand dropping liquid ink-jet apparatus of temperature-sensitive, wherein causing member Part 32 includes resistor (such as passing through thin film transistor (TFT)), and wherein selectively applies electric current to initiation element 32, so that It generates enough heats and carrys out gasified liquid, generate bubble, which forcibly makes the remaining liq in room 30 pass through nozzle opening 33 spray.In one implementation, initiation element 32 may include temperature-sensitive initiation element, which can be using formation Thermal resistor on oxide skin(coating) in the top surface of the substrate and the stacks of thin films being applied at the top of oxide skin(coating), and it is thin Film second is as metal layer, conductive trace and the passivation layer for limiting initiation element.

In another is realized, droplet generator 26 includes the on-demand dropping liquid ink-jet apparatus of piezoelectricity, and wherein initiation element 26 is wrapped It includes piezoelectric member (such as passing through thin film transistor (TFT)), and wherein electric current is selectively applied to initiation element 32 so that diaphragm Deflection, the diaphragm spray the remaining liq in room by nozzle.In still other realization, droplet generator 26 is wrapped It includes and is currently available or the liquid drop generator of the other forms of the following exploitation.

The horizontal parameter of the sensing instruction ink of level sensing systems 28 or fluid.In one implementation, level sensing systems 28 sensings guiding thing (primer), the guiding thing indicate the indignation being just supplied in the fluid slot 24 of droplet generator 26 (anger) level of fluid.Level sensing systems 28 include sensing room 34, liquid level sensor 36, circulation path 38 and fluid pump 40。

Sensing room 34 includes the room carried by print head 20 or volume, and the room or volume include liquid level sensor 36.? In a kind of realization, sensing room 34 is formed in substrate, also forms fluid slot 24 in the substrate.Sensing room 34 includes fluidly It is coupled to the first port 44 of fluid slot 24 and the second port 46 different from port 44.Port 44 and 46 promotes fluid across liquid level Sensor 36 flows.Although port 44 and 46 be illustrated as sensing room 34 opposite side extend and it is facing with each other, at it During he realizes, such port 44 and 46 can be in other positions.For example, in other implementations, port 44 and 46 can be along Adjacent face extends, so that port 44 and 46 extends perpendicular to each other.

It senses room 34 and receives fluid from fluid slot 24, wherein liquid level sensor 36 senses one or more of the fluid received A characteristic, includes the level of the fluid in print head 20 with identification, such as is just supplied to droplet generator in fluid slot 24 The level of 26 fluid.In one implementation, liquid level sensor 36 is by sensing by the horizontal change of the fluid in sensing room 34 Change caused capacitance variations to sense the level of fluid.In other implementations, the otherwise sensed level of liquid level sensor 36.

Circulation path 38 includes fluid along its flowing or channel, pipeline or other accesses of circulation.Circulation path 38 is from stream Body slot 24 extends to port 46.Circulation path 38 promotes fluid to enter in sensing room 34, from fluid slot 24 across liquid level sensor 36 And the circulation that sensing room 34 returns in fluid slot 24 is left by port 44.Alternative access 38 ', 38 " and 38 " ' as shown Indicated by dotted line, circulation path 38 can have various shape and route.

Fluid pump 40 includes such equipment, which is positioned to pump and cycle through circulation path 38 for fluid And sensing room 34 is cycled through across liquid level sensor 36.In one implementation, fluid pump 40 is located in circulation path 36.Another During kind is realized, fluid pump 40 includes resistor, and the resistor one receives electric current and then heats with vaporizing fluid, generates bubble, The bubble drives along circulation path 38 and pumps adjacent fluid.In another is realized, fluid pump 40 includes for example pressing Other micro- pumping equipments of electric equipment, wherein diaphragm is deflected fluid or liquid are forcibly sprayed or pumped along circulation path 38 Body.

It, may be from the ink or fluid evaporator moisture in sensing room 34 when print head 20 is being operated but be not covered. This moisture loss of the lid (decap) during the period is being gone to may cause various the problem of going lid to cause, such as pigment-ink-load Body separation, sticky bolt are formed, weak bubble driving, latex-ink-carrier separates and/or wax-ink-carrier separation.As a result, may Reduce the performance of sensor.Fluid pump 40 recycles fluid across liquid level sensor 36 or recirculated through circulation path 38, with not Disconnected ground periodically refreshes the fluid sensed in room 34.As a result, improving the service life and/or property of liquid level sensor 36 Energy.

Fig. 2 is the flow chart for operating the exemplary method 70 of print head.In one implementation, using the print head of Fig. 1 20 enforcement methods 70.As indicated by box 72, liquid level sensor 36 senses the liquid level in the sensing room 34 of print head 20.As above It is noticed, in one implementation, the sensing of liquid level sensor 36 corresponds to the level or base of fluid or ink in sensing room 34 In the capacitance that the level changes.The level of fluid or ink in sensing room 34, which corresponds in fluid slot 24, is just supplied to liquid Drip the level of the fluid of generator 26.In another implementation, liquid level sensor 36 otherwise detects sensing room 34 and stream The level of fluid in body slot 24.

As indicated by box 74, fluid is cycled through first port 46 from fluid slot 24 and enters sensing room by fluid pump 40 34.The possibility being currently resident in sensing room 34 has been subjected to the fluid of evaporation and moisture loss or ink is recycled or be driven to lead to Cross second port 44 leave sensing room 34 return in fluid slot 24, in fluid slot 24 with have compared with high-moisture level fluid or Ink mixing.Because the fluid or ink that reside in sensing room 34 utilize the ink having compared with high-moisture level from fluid slot 24 Or fluid refreshes, so liquid level sensor 36 is less likely experience various the problem of going lid to cause.As a result, enhancing liquid level biography The performance of sensor 36.

Fig. 3 schematically illustrates the sample printing system 100 for being incorporated to print head 20.Print system 100 is beaten including ink-jet Print head assembly 102, ink supply assembly 104, mounting assembly 106, medium transport component 108, electronic printable machine controller 110 and are At least one power supply 112 of the various electric components power supply of ink-jet print system 100.Inkjet printhead assembly 102 includes multiple Print head 20.Each print head 20 includes multiple droplet generators 26, and multiple droplet generators 26 are controlled as selectively to Ink droplet is sprayed towards print media 118 by multiple holes or nozzle to print on print media 118.Print media 118 can be with It is any kind of suitable sheet material or coiled material, such as paper, paper jam, transparent film, polyester, glued board, cystosepiment, fabric, sail Cloth etc..In illustrated example, such droplet generator 26 and its associated nozzle are disposed in one or more column Or in array, so that ink is suitably suitable from nozzle when inkjet printhead assembly 102 and print media 118 are moved relative to each other Spraying to sequence causes character, symbol and/or other figures or image to be printed upon on print media 118.

As Fig. 3 is further schematically shown, each print head 20 further includes level sensing systems 28 as described above. In illustrated example, each level sensing systems 28 include setting in sensing room 34 (above for described in Fig. 1) Liquid level sensor 36, the tool of liquid level sensor 36 is coupled to fluid slot 24 (as shown in figure 1 to each port flow there are two port It is shown).Each level sensing systems 28 further include fluid pump 40 (showing in Fig. 1), and fluid pump 40 makes in circulation path 38 Fluid constantly or periodically cycles through sensing room 34, with refresh with liquid level sensor 36 it is opposite comprising fluid.Institute In the example of diagram, each level sensing systems 28 also comprise droplet generator 52, and droplet generator 52 (is schemed from sensing room 34 Shown in 1) remove ink residual.

Fluid ink is supplied to print head assembly 102 by ink supply assembly 104, and including the liquid storage device 120 for storing ink. Ink flows to inkjet printhead assembly 102 from liquid storage device 120.Ink supply assembly 104 and inkjet printhead assembly 102 can be formed unidirectionally Black transportation system recycles black transportation system.In unidirectional black transportation system, it is supplied to the Mo Ji of inkjet printhead assembly 102 It is all in sheet to be all consumed during printing.However, being supplied to the ink of print head assembly 102 in recycling black transportation system Only a part is consumed during printing.Unconsumed ink returns to black feeding assembly 104 during printing.

In one embodiment, ink supply assembly 104 is adjusted by ink at a positive pressure via the interface connection of such as supply pipe Suitable component 105 supplies ink to inkjet printhead assembly 102.Ink supply assembly 104 includes that such as liquid storage device, pump and pressure are adjusted Device.The adjustment carried out in black adaptation component 105 may include filtering, preheating, press and gush absorption and degassing.Ink is under negative pressure from printing Head assembly 102 is drawn into ink supply assembly 104.Pressure difference between the entrance and exit of print head assembly 102 is selected as spraying Correct counter-pressure is realized at mouth 116, and is usually in H₂Minus 1 " the negative pressure between minus 10 " of O.Ink supply assembly 104 Liquid storage device 120 can be removed, replace and/or refill.

Mounting assembly 106 transports 108 positions inkjet printhead component 102 of component, and medium transport group relative to medium Part 108 is relative to 102 positions print media 118 of inkjet printhead assembly.Therefore, printing domain 122 is defined as in inkjet printing It is adjacent with the nozzle of droplet generator 26 in region between head assembly 102 and print media 118.In one embodiment, it sprays Black print head assembly 102 is sweep type print head assembly.In this way, mounting assembly 106 includes for transporting component relative to medium 108 mobile inkjet printhead assemblies 102 are with the frame of scanning and printing medium 118.In another embodiment, inkjet printhead assembly 102 be non-scanning type printhead assembly.In this way, inkjet printhead assembly 102 is transported component relative to medium by mounting assembly 106 108 are fixed on specified position.Therefore, medium transports component 108 relative to 102 positions print media 118 of inkjet printhead assembly.

Electronic printable machine controller 110 typically comprises processor, firmware, software including volatile and non-volatile and deposits One or more memory assemblies of reservoir component, and be used for and inkjet printhead assembly 102, mounting assembly 106 and medium Transport other printer electronics devices that component 108 carries out communication and controlled them.Electronic controller 110 is from such as counting The host system of calculation machine receives data 124, and data 124 are temporarily stored in memory.In one implementation, data 124 Ink-jet print system 100 is sent to along electronics, infrared, optics or other information transmitting path.The expression of data 124 is for example wanted The document and/or file of printing.In this way, data 124 form the print job for being used for ink-jet print system 100, and including one A or multiple print job commands and/or command parameter.

In one implementation, electronic printable machine controller 110 controls the inkjet printhead assembly 102 for spraying ink droplet. Therefore, electronic controller 110 defines the ejection that character, symbol and/or other figures or image are formed on print media 118 The pattern of ink droplet.Spray ink droplet pattern by from data 124 print job command and/or command parameter determine.At one In embodiment, electronic controller 110 includes printer specific integrated circuit (ASIC) 126 and can be in ASIC 126 or controller The resistance sensing firmware module 128 executed on 110.Printer ASIC 126 includes current source 134 and analog-digital converter (ADC) 132.ASIC 126 can convert the voltage being present at current source 134 to determine resistance, and then pass through determining pair of ADC 132 The digital resistance value answered.The programmable algorithms realized by resistance sensing module 128 enable resistance and determine and subsequently through ADC 132 The number conversion of progress.

In one implementation, print system 100 includes having to be adapted to carry out level sensing systems as disclosed herein The on-demand dropping liquid thermal inkjet-printing system of 28 thermal inkjet (TIJ) print head 20.In one implementation, inkjet printhead assembly 102 include single TIJ print head 20.In another implementation, inkjet printhead assembly 102 includes the wide battle array of TIJ print head 20 Column.Although manufacturing process associated with TIJ print head is very suitable for the integrated of ink sensor, such as piezoelectric printhead Other print head types this level sensing systems 28 also may be implemented.Disclosed level sensing systems 28 are not limited to realize In TIJ print head 20.

Fig. 4 schematically illustrates print head 220, and print head 220 is the example reality about the print head 20 of Fig. 1 description It is existing.In one implementation, instead of each illustrated print head 20, print head 220 is used as the portion of print system 100 Point.Print head 220 is similar to print head 20, in addition to print head 220 is illustrated as specifically including the liquid instead of droplet generator 26 It drips generator 226 and replaces the level sensing systems 228 of level sensing systems 28.As by the way that shown in Fig. 4, print head 220 includes A series of or multiple droplet generators 226 of column.In illustrated example, each droplet generator 226 includes that printing is drawn Hair room 230 is arranged in print and causes in room 230 or adjacent with printing initiation room 230 temperature-sensitive initiation element 232 and nozzle opening 233.Printing causes room 230 and fluidly connects via port 235 and fluid slot 24, to receive fluid or ink from fluid slot 24. Initiation element 232 is selectively supplied electric current to generate heat with the adjacent fluid that gasifies, and steam bubble is generated, with forcibly Remaining fluid is discharged by nozzle opening 232.When the initiation element 232 being heated is cooling, steam bubble is quickly collapsed, thus More fluids are aspirated from fluid slot 24 and enter initiation room 230, are prepared to spray another drop from nozzle 233.

Similar to level sensing systems 28, level sensing systems 228 sense the level of fluid or ink and make fluid across stream Body sensor is recycled to maintain or enhance the operating characteristics of liquid level sensor.Level sensing systems 228 are similar to above-mentioned liquid level Sensing system 28, in addition to level sensing systems 228 include a kind of liquid level sensor 236 realized as liquid level sensor 36, And droplet generator 241 is also comprised, droplet generator 241 includes fluid initiation element 242 and nozzle opening 243.It is corresponding It is similarly numbered in the remaining element of those of level sensing systems 228 of component of level sensing systems 28 or component.

The fluid for coming self-inductance measurement room 34 or ink residual are removed in the discharge of droplet generator 241.In illustrated example, liquid Dripping generator 241 includes four exposed initiation elements 242, and this anchoring fluid residuals are discharged by nozzle opening 243.? In illustrated example, initiation element 242 includes heat-resisting initiation element, which includes resistor, the resistor One, which receives electric current, then heats, and generates bubble to make liquid or fluid gasify, which passes through nozzle opening 243 forcibly Residual fluid is discharged.In other implementations, initiation element 242 includes piezoelectricity initiation element, and one receives electric current, which causes Element changes shape so as to moving film, which be discharged residual fluid by nozzle opening 243.Still other In realization, droplet generator 241 can have other configurations or can be omitted.

Liquid level sensor 236, which senses, currently just to be supplied by fluid slot 24 and is comprised in liquid storage device 120 (showing in Fig. 3) The level of interior fluid.In illustrated example, the sensing of liquid level sensor 236 corresponds to the fluid or ink sensed in room 34 Capacitance that is horizontal or being changed based on the level, the level correspond to the level for the ink just supplied by fluid slot 24.At other In realization, liquid level sensor 236 can otherwise sense the level for the fluid supplied by fluid slot 24.

Fig. 5 is the section view of droplet generator 241 and liquid level sensor 236.As passed through shown in Fig. 5, droplet generator 241 include nozzle 243, sensing room 34 and the initiation element 242 being arranged in sensing room 34.Nozzle 243 is formed in nozzle layer 250 In.Initiation element 242 is by the metal plate on the insulating layer 252 (such as polysilicon glass, PSG) on 254 top surface of silicon substrate The thermal resistor that (such as tantalum-aluminium, TaA1) is formed.Passivation layer 256 on initiation element 242 protect initiation element 242 from Fluid or ink in room 34 influence, and serve as mechanical passivation or protectiveness air pocket barrier structure and collapse rushing for steam bubble to absorb It hits.Room floor 258 has the wall for separating substrate 254 with nozzle layer 250 and room 34.

Liquid level sensor 236 includes ink level sensor circuit, and ink level sensor circuit is partially integrated in print head On 220.Other than those of being integrated on print head 220 part, liquid level sensor 236 is also incorporated to from printer ASIC The current source 130 and analog-digital converter (ADC) 132 of 126 (showing in Fig. 3), printer ASIC 126 are not integrated in print head On 220.Instead, printer ASIC 126 is located on the Support for impression mechanism or electronic controller of such as printer system 100.

As further illustrated in fig. 5, the ink level sensor circuit for forming liquid level sensor 236 is incorporated to capacitor sensor (Csense)260.In illustrated example, metal plate, passivation layer 256 of the capacitor sensor 260 by formation initiation element 242 And the substance or content of room 34 are formed.The value of capacitor sensor 260 changes as the substance in room 34 changes.In room 34 Substance can be ink entirely, be ink and air, or only air.Therefore, the value of capacitor sensor 260 is with the ink in room 34 It is horizontal and change.When there is ink or fluid in room 34, capacitor sensor 260 has good grounding conductance, therefore capacitance Highest (i.e. 100%).However, the capacitor of capacitor sensor 260 drops to when not having fluid or ink (i.e. only air) in room 34 Very small value, ideally close to zero.When room includes ink and air, the capacitance of capacitor sensor 260 is between zero He Somewhere between 100%.Using the variational value of capacitor sensor 260, liquid level sensor 136 can determine ink level.It is logical Often, the level of the ink in the liquid storage device 120 of the ink level instruction printer system 100 in room 34.In some implementations, with liquid Before level sensor 236 measures ink level, black residual is removed from room 34 using initiation element 242.Later, with regard to liquid storage device 120 Present in fluid or ink degree for, such fluid or ink flow back into room and enable to carry out accurate ink level Measurement.

In illustrated example, liquid level sensor 236 also comprises parasitic elimination element 300.In other implementations, it saves Parasitic elimination element 300 is omited.Parasitism eliminates element and is designed to eliminate the conductive layer 300 of the influence of parasitic capacitance Cp1 304 (such as polysilicon layer).In this design, when voltage (i.e. Vp) is applied to metal plate 242, which, which may be applied to, is led Electric layer 300.This prevents charge from developing on Cp1 304, so that effectively removed from the determination of 260 capacitor of capacitor sensor/ Cp1 is isolated.Cp2 (element 302) carrys out the natural capacity that autoparasitism eliminates element 300 (conductive polycrystalline silicon floor 300).Cp2 302 Slow down the parasitic charging rate for eliminating element 300, but due to providing enough charging time to element 300, so to Cp1 304 removal/isolation does not influence.

Fig. 6 is the circuit diagram for illustrating liquid level sensor 136.In Fig. 5, parasitic capacitance Cp1 304 is shown as being coupled in Metal plate 142 (node M 1) and conductive layer 300 are (between node M p).With reference to Fig. 5 and Fig. 6, there is the parasitic liquid for eliminating circuit 300 Level sensor 136 is driven by nonoverlapping clock signal.In the first step, carry out closed transistor using clock pulses S1 to switch T1a, T1b and Tp1.Memory node M1, M2 and Mp are coupled to ground connection by closure switch T1a, T1b and Tp1, thus to sensing electricity Container (Csense) 260, reference capacitor (Cref) 310 and capacitor parasitics (Cp1) 304 discharge.In the second step, S1 clock pulses terminates, and disconnects T1a, T1b and Tp1 switch.Directly after T1 a, T1 b and Tp1 switch disconnect, S2 clock arteries and veins Punching is used for closed transistor switch T2 and Tp2.It is closed T2 and Tp2 and node M 1 and Mp is respectively coupled to pre-charge voltage Vp.This Charge Q 1 is placed across capacitor sensor (Csense) 260.However, the case where node M 1 and Mp are in identical voltage potential Vp Under, charge is not developed across capacitor parasitics (Cp1) 304.

In third step, S2 clock pulses is terminated, and disconnects T2 and Tp2 transistor switch.It is directly disconnected in T2 and Tp2 switch After opening, S3 clock pulses closed transistor switch T3 and Tp3.Closure switch T3 is coupled to each other by node M 1 and M2 and is sensing Charge Q 1 is shared between capacitor 260 and reference capacitor 310.It is shared between capacitor sensor 260 and reference capacitor 310 Charge Q 1 leads to the reference voltage Vg at node M 2, and reference voltage Vg is also at the grid of assessment transistor T4.Closure is opened It closes Tp3 and capacitor parasitics (Cp1) 304 is coupled to ground connection.During S3 clock pulses, the spurious charge on Cp1 304 is put Electricity, so that only capacitor sensor 260 is assessed using assessment transistor T4.Due to eliminating the shadow of capacitor parasitics (Cp1) 304 It rings, so there is the parasitic contribution to conducting T4 greatly reduced for original signal (dry signal).

Fig. 7 shows the flow chart of the exemplary method 400 of sensing ink level in accordance with an embodiment of the present disclosure.Method 400 starts In box 402, wherein pre-charge voltage Vp is applied to capacitor sensor, is charged with charge Q to capacitor sensor.Vp is applied It include that Vp is coupled to by first memory node M 1 by closure switch T2 in capacitor sensor.In another embodiment, it applies Add Vp to also comprise and Vp is applied to node M p to prevent the capacitor parasitics between M1 and Mp to charge.

At the box 404 of method 400, charge Q 1 is shared between capacitor sensor and reference capacitor, thus commenting Estimate and causes reference voltage Vg at the grid of transistor.Shared charge Q 1 includes disconnecting T2 so that Vp and capacitor sensor disconnect and connecting It connects, and closure switch T3 is to be coupled to reference capacitor for capacitor sensor.This, which is shared, is coupled to second memory node for M1 M2 between capacitor sensor and reference capacitor to share charge, and the charge shared causes M1, M2 and transistor gate Reference voltage Vg at pole.

Method 400 continues in step 406, wherein resistance of the determining assessment transistor drain generated by Vg to source electrode.It is logical The resistance is determined below crossing: forcing electric current at the drain electrode of transistor, measures the voltage Vid at the drain electrode of transistor, is executed Resistance is converted into digital value to calculate resistance from electric current and Vid by algorithm.

At the frame 408 of method 400, by the way that the resistance is compared with having one group of resistance of predetermined associated ink level Relatively determine ink level.At the box 410 of method 400, before applying pre-charge voltage Vp, to capacitor sensor and reference Capacitor discharge.

In the example shown in Figure 4, fluid circulation paths or access 38 are illustrated as in sensing room 34 and drop formation It is passed through between the column of device 126.In other implementations, it can be provided in other positions, form sensing room 34 and fluid circulation paths 38.Fig. 8 is illustrated as another print head 520 realized of print head 20.Printing 520 is similar to print head 120, in addition to printing First 520 include level sensing systems 528.Level sensing systems 528 are similar to level sensing systems 128, in addition to fluid circulation is logical Road 38 extends around sensing room 34 and the opposite side of the column of droplet generator 126.As a result, fluid circulation path 38 is to drop formation The layout or arrangement interference degrees of device 126 are smaller.Those remainders are the elements of print head 520 and level sensing systems 528, These elements correspond to the element of print head 120 and level sensing systems 128, are similarly numbered.Although access 38 is illustrated To extend from the side 529 of room 34, but in another implementation, access 38 alternatively extends from the side 531 of room 34.Again its In his realization, access 38 extends from multiple sides of room 34 or is connected to multiple sides of room 34.

Fig. 9 is the flow chart for being used to form the exemplary method 600 of print head.As indicated by through box 602, fluid slot 24 It is formed in the substrate of print head.As indicated by through box 604, sensing room 34 is formed in print head.Room 34 has first And second port, wherein first port is fluidly connected to fluid slot.As indicated by through box 606, liquid level sensor is formed 36,136, liquid level sensor 36,136 is provided in sensing room 34.As indicated by through box 608, circulation path 38 is formed. Circulation path 38 extends to the second port of sensing room 34 from fluid slot 24.In one implementation, circulation path 38 is formed in lining In bottom, fluid slot and sensing room are also formed in the substrate.As indicated by through box 610, pump 40 is formed on substrate so that stream Body circulation passes through circulation path 38.In one implementation, pump 40 includes the thermistor initiation element or pressure in access 38 Electric initiation element.

Figure 10 and Figure 11 illustrates the formation of the sample printing head 720 according to the method for Fig. 9.It such as will be about complete in Figure 11 Described in the whole print head 720 shown, print head 720 includes a pair of of level sensing systems 728.Level sensing systems 728 Be functionally similar to level sensing systems 228, in addition to level sensing systems 728 using the droplet generator 226 ' slightly modified as Fluid pump 40 is to enable flow through and recycle across sensing room 34.As a result, the area of coverage of this level sensing systems 728 (footprint) reduce.As shown in the comparison by Figure 10 and 11, addition circulation path 38 has no substantial effect on pump 40 to be beaten Print the layout of 720 remainder of overall dimension or print head of head 720.Therefore, promote to be manufactured with lower cost.

As by the way that shown in Figure 10, fluid slot 724 is formed in substrate 722.It is arranged to the droplet generator of two column 727,728 226 are formed on the opposite side of fluid slot 724.For each column in column 729,731, sensing room 34 is formed.Illustrated In example, sensing room 34 is formed in the end of each column in column 729,731, and liquid level biography is further formed in each sensing room 34 Sensor 136.

As by shown in Figure 10, method illustrated further comprises that circulation is formed in substrate 722 in Figure 10 and Figure 11 Access 738.Each circulation path 738 extends to selected droplet generator 226 ' from the port 46 of sensing room 34.With column 729,731 Other droplet generators 226 it is different, each selected droplet generator 226 ' is omitted nozzle opening 233 and including to printing Cause the additional port 744 in room 230.As a result, each selected droplet generator 226 ' plays the role of pump and comes so as to flow automatically The fluid or ink of body slot 724 are recycled in their associated sensing rooms 34 and recycle across their associated sensing rooms 34.One It is activated, fluid is caused room 230 from printing by port 744 and is discharged to circulation by the initiation element 232 of droplet generator 226 ' In access 738, and sensing room 34 is further entered by port 46.Sensing room 34 in it is existing, print head 720 go lid grasp The fluid or ink that evaporation may be had been subjected to during work are pushed and are vented back in fluid slot 724 by port 44.Fluid into One step is aspirated into the fluid for causing room 230 so that previously passed port 744 to be discharged to circulation path 738 by port 235 Replacement.

As by the way that it is logical to circulate fluid through circulation by recycling droplet generator 226 ' shown in Figure 11 and 11A Road 738 across sensing room 34 and returns to pump in fluid slot 724, and fluid sensing system 728, which has 720 general frame of print head, to be subtracted The change of small number.In one implementation, if not in order to omit nozzle opening and four ports for being connected to circulation path 738 744 additional setting, droplet generator 226 ' are identical as the remaining droplet generator 226 in each column of column 727,728.Change sentence It talks about, the configuration and the remaining ink droplet in column 727,728 that the printing of droplet generator 226 ' causes room 230 and initiation element 232 The printing of generator 226 causes room 230 and initiation element 232 is identical.As a result, the printing of each droplet generator 226 ' causes room 230 and initiation element 232 can for other droplet generators 226 formed these components while be manufactured.

Although describing the disclosure by reference to example embodiment, art technology worker is it will be recognized that can be with The spirit and scope without departing from theme claimed are made a change in form and details.For example, although may be Different example embodiments is described as to include providing the one or more features of one or more benefits, but be contemplated that In described example embodiment or in other alternate embodiments, described feature can be interchangeable with one another or alternative Ground is combined with each other.Because the technology of the disclosure is relative complex, and not all technical change all is foreseeable. Reference example embodiment is described and the disclosure that is described in the accompanying claims clearly be intended that it is as wide in range as possible.Example Such as, unless otherwise specifically stated, the claim for otherwise recording single specific factor is also covered by multiple such specific factors.

Claims (14)

1. a kind of device for print head sensing room circulation, comprising:

Print head with fluid slot and sensing room, the sensing room have first port and second port, the first port It is connected to the fluid slot；

Droplet generator, the droplet generator are fluidically coupled to the fluid slot to receive fluid from the fluid slot；

In the indoor liquid level sensor of sensing；

Extend and be fluidically coupled to the circulation path of the second port from the fluid slot；And

For circulating fluid through the fluid pump of re-circulation path,

Wherein the print head further comprises a series of printing nozzles, wherein the circulation path is sprayed in a series of printings Extend between mouth and the sensing room.

2. device as described in claim 1, wherein the fluid pump includes that fluid is made to gasify to pump the resistance of adjacent fluid Device.

3. device as described in claim 1, wherein the liquid level sensor includes transducer nozzle and resistor, the resistance Device makes the indoor fluid gasification, and fluid is discharged by the transducer nozzle.

4. device as described in claim 1, wherein the print head further comprises one on sensing first side of room Serial printing nozzle, wherein the circulation path extends in second side opposite with first side of the sensing room.

5. device as described in claim 1, wherein the print head further comprises:

One column printing causes room, and each printing of the column, which causes room, has the entrance for being connected to the fluid slot, a column It includes that the first printing initiation room and the second printing cause room that printing, which causes room,；

Cause indoor initiation resistor each；And

The initiation mouth adjacent with the first printing initiation room extends wherein the circulation path causes room from second printing To the second port, and the initiation resistor that wherein second printing causes in room plays the role of pump.

6. device as claimed in claim 5, wherein it is identical that first printing, which causes room and the second printing initiation room, 's.

7. device as claimed in claim 6, wherein first printing causes initiation resistor in room and second dozen described It is identical that print, which causes the second initiation resistor in room,.

8. device as described in claim 1, wherein the liquid level sensor includes capacitor sensor, the capacitor sensor Capacitor changes with the level of the sensing fluid inside.

9. a kind of method for print head sensing room circulation, comprising:

Sense the indoor liquid level of sensing of print head；And

So that fluid is entered the sensing room by first port from the fluid slot of the print head and institute is left by second port Sensing room is stated to return in the fluid slot and recycle,

Wherein the print head includes a series of printing nozzles, and wherein circulation path is in a series of printing nozzles and the sense It surveys between room and extends.

10. method as claimed in claim 9, wherein the sensing includes sensing in the indoor capacitor sensor of sensing Capacitance variations.

11. method as claimed in claim 9, wherein the circulation includes making in the identical initiation room of a column in an initiation room Resistor causes, and is pumped into the sensing room with vaporizing fluid and by adjacent fluid by the first port.

12. a kind of method for print head sensing room circulation, comprising:

Fluid slot is formed in the substrate；

The sensing room of print head is formed, the sensing room has first port and second port, and the first port is connected to institute State fluid slot；

In the indoor offer ink sensor of the sensing；

Form the re-circulation path from the fluid slot to the second port of the sensing room；And

It is formed over the substrate for the pump by fluid circulation by the re-circulation path.

13. method as claimed in claim 12, wherein forming re-circulation path includes making circulation path from the print head The identical selected initiation room caused in room of one column extends.

14. method as claimed in claim 13, further comprise in the identical initiation room for the column except selected initiation room with Outer each initiation room forms nozzle opening.